I have a code that starts as a small amount of variables and makes more elements using those initial variables.
function new( x, y, width, height )
local object = {}
--border
object.border = { x = x, y = y, width = width, height = height }
--body
object.body = { x = x+1, y = y+1, width = width-2, height = height-2 }
--font
object.font = {}
object.font.size = (object.body.height+2)-(math.floor((object.body.height+2)/4)+1)
object.font.height = love.graphics.setNewFont( object.font.size ):getHeight()
--padding
object.padding = {}
object.padding.height = math.floor(object.border.height*(2/29))
object.padding.width = object.padding.height*3
--text
object.text = { input = '' }
object.text.centerHeight = math.ceil(object.body.y+((object.body.height-object.font.height)/2))
object.text.left = object.body.x+object.padding.width+object.padding.height
--backspacing
object.backspace = {key = false, rate = 3, time = 0, pausetime = 20, pause = true}
--config
object.config = { active = true, devmode = false, debug = false, id = gui.id(), type = 'textbox' }
gui.add(object)
return object.config.id
end
and when I modify something in the middle part, the whole thing becomes a mess because starting from the one i changed until the bottom ones value doesn't agree with each other
local x = gui.get(2)
x.body.height = 50
I'm looking if there's a way for these variables to be redefined, starting from them until the bottom, without: (a) making functions for each of the variables. and (b) editing the required parameters in the function.
and If there's none, are the an alternate way to do this efficiently?
EDIT:
the structure of the variables is as follow:
border->body->padding->font
what i needed is a way i can define any of them so that the one that follows also changes like:
object.body.x = 15
and it would collapse from that redefined variable until the bottom:
body->padding->font
i could just redefine them from the edited variable until the bottom like this:
--not the actual code, just an example of variables dependent on the variable above
object.body.x = 15
object.padding.width = object.body.x+1
object.font.size = object.padding.width+1
but that means I have to do the same when redefining the padding until the font which is extremely inefficient especially when I extended more elements.
example:
--padding->font
object.padding.width = 5
object.font.size = object.padding.width+1
I was bored and saw this question (again) along with a duplicate.
I started writing some code for fun, leading to this:
local function getNeededVars(tab,func)
local needed,this = {}
this = setmetatable({},{
__index = function(s,k)
-- See if the requested variable exists.
-- If it doesn't, we obviously complain.
-- If it does, we log it and return the value.
local var = tab.vars[k]
if not var then
error("Eh, "..k.." isn't registered (yet?)",5)
end needed[k] = true return tab.vals[k]
end;
}) func(this) return needed
end
local function updateStuff(self,key,done)
for k,v in pairs(self.levars) do
if v.needed and v.needed[key] then
if not done[v] then done[v] = true
self.vals[v.name] = v.func(self)
updateStuff(self,v.name,done)
end
end
end
end
local function createSubTable(self,key,tab)
return setmetatable({},{
__newindex = function(s,k,v)
tab[k] = v updateStuff(self,key,{})
end; __index = tab;
})
end
local dependenceMeta
dependenceMeta = {
__index = function(self,k)
-- Allow methods, because OOP
local method = dependenceMeta[k]
if method then return method end
local variable = self.vars[k]
if not variable then
error("Variable "..k.." not found",2)
end return self.vals[k]
end;
__newindex = function(self,k,v)
local variable = self.vars[k]
if not variable then
error("Use :Register() to add stuff",2)
elseif type(v) == "table" then
self.vals[k] = createSubTable(self,k,v)
return updateStuff(self,k,{})
end self.vals[k] = v updateStuff(self,k,{})
end
}
function dependenceMeta:Register(var,value)
local varobject = {func=value,name=var}
self.vars[var] = varobject
table.insert(self.levars,varobject)
if type(value) == "function" then
varobject.needed = getNeededVars(self,value)
self.vals[var] = value(self)
elseif type(value) == "table" then
self.vals[var] = createSubTable(self,var,value)
elseif value then
self.vals[var] = value
end
end
function dependenceMeta:RegisterAll(tab)
for k,v in pairs(tab) do
self:Register(k,v)
end
end
local function DependenceTable()
return setmetatable({
levars = {};
vars = {};
vals = {};
},dependenceMeta)
end
local test = DependenceTable()
test:Register("border",{
x=20; y=50;
height=200;
width=100;
})
test:Register("body",function(self)
return {x=self.border.x+1,y=self.border.y+1,
height=self.border.height-2,
width=self.border.width-2}
end)
test:Register("font",function(self)
local size = (self.body.height+2)-(math.floor((self.body.height+2)/4)+1);
return { size = size; -- Since we use it in the table constructor...
height = size-4; --love.graphics.setNewFont( self.font.size ):getHeight();
-- I don't run this on love, so can't use the above line. Should work though.
}
end)
test:Register("padding",function(self)
local height = math.floor(self.border.height*(2/29))
return { height = height; width = height*3 } -- again dependency
end)
test:Register("text",{input=""}) -- Need this initially to keep input
test:Register("text",function(self)
return { input = self.text.input;
centerHeight = math.ceil(self.body.y+((self.body.height-self.font.height)/2));
left = self.body.x+self.padding.width+self.padding.height;
}
end)
test:Register("backspace",{key = false, rate = 3, time = 0, pausetime = 20, pause = true})
-- Again, didn't use gui.id() on the line below because my lack of LÖVE
test:Register("config",{active=true,devmode=false,debug=false,id=123,type='textbox'})
print("border.x=20, test.text.left="..test.text.left)
test.border = {x=30; y=50; height=200; width=100;}
print("border.x=30, test.text.left="..test.text.left)
test.border.x = 40
print("border.x=40, test.text.left="..test.text.left)
It's a lot of code, but I liked writing it. It gives this nice output:
border.x=20, test.text.left=73
border.x=30, test.text.left=83
border.x=40, test.text.left=93
All properties only get recalculated when one of its dependencies is edited. I made it also work with subtables, which was a bit tricky, but at the end actually seems quite easy. You can edit (for example) the body field by setting it to a completely new table or by setting a field in the already existing table, as seen in the last few lines of the code snippet. When you assign it to a new table, it'll set a metatable on it. You can't use pairs (& co) neither, unless you use 5.2 and can use __pairs.
It might solve your problem. If not, I had fun writing it, so at least it'll always be something positive that I wrote this. (And you have to admit, that's some beautiful code. Well, the way it works, not the actual formatting)
Note: If you're gonna use it, uncomment the love.graphics and gui.id part, as I don't have LÖVE and I obviously had to test the code.
Here's a quick "summary" of my thing's API, as it might be confusing in the beginning:
local hmm = DependenceTable() -- Create a new one
print(hmm.field) -- Would error, "field" doesn't exist yet
-- Sets the property 'idk' to 123.
-- Everything except functions and tables are "primitive".
-- They're like constants, they never change unless you do it.
hmm:Register("idk",123)
-- If you want to actually set a regular table/function, you
-- can register a random value, then do hmm.idk = func/table
-- (the "constructor registering" only happens during :Register())
-- Sets the field to a constructor, which first gets validated.
-- During registering, the constructor is already called once.
-- Afterwards, it'll get called when it has to update.
-- (Whenever 'idk' changes, since 'field' depends on 'idk' here)
hmm:Register("field",function(self) return self.idk+1 end)
-- This errors because 'nonexistant' isn't reigstered yet
hmm:Register("error",function(self) return self.nonexistant end)
-- Basicly calls hmm:Register() twice with key/value as parameters
hmm:RegisterAll{
lower = function(self) return self.field - 5 end;
higher = function(self) return self.field + 5 end;
}
-- This sets the property 'idk' to 5.
-- Since 'field' depends on this property, it'll also update.
-- Since 'lower' and 'higher' depend on 'field', they too.
-- (It happens in order, so there should be no conflicts)
hmm.idk = 5
-- This prints 6 since 'idk' is 5 and 'field' is idk+1
print(hmm.field)
You could use setfenv (if Lua 5.1) to remove the need of 'self.FIELD'. With some environment magic you can have the constructor for 'field' (as an example) just be function() return idk+1 end.
You could make use of metatables, more specific, the __newindex field:
(Well, need to combine it with the __index field, but eh)
function new(x, y, width, height )
local object = {
font = {}, padding = {}, text = {input=''}, -- tables themself are static
-- also I assume text.input will change and has to stay the way it is
}
-- more static data here (yes yes, I know. The code is a bit ugly, but if it works fine...)
object.config = { active = true, devmode = false, debug = false, id = gui.id(), type = 'textbox' }
object.backspace = {key = false, rate = 3, time = 0, pausetime = 20, pause = true}
object.border = { x = x, y = y, width = width, height = height }
-- stuff that has to be calculated from the above variables goes below
local border = object.border
local function calculate()
--border
--body
object.body = { x = border.x+1, y = border.y+1, width = border.width-2, height = border.height-2 }
--font
object.font.size = height-(math.floor(height/4)+1)
object.font.height = love.graphics.setNewFont( object.font.size ):getHeight()
--padding
object.padding.height = math.floor(object.border.height*(2/29))
object.padding.width = object.padding.height*3
--text
object.text.centerHeight = math.ceil(object.body.y+((object.body.height-object.font.height)/2))
object.text.left = object.body.x+object.padding.width+object.padding.height
--backspacing
--config
end
calculate()
local proxy = setmetatable({},{
__index = object; -- proxy.abc returns object.abc (to get width, use proxy.border.width)
__newindex = function(s,k,v)
-- fires whenever 'proxy[k] = v' is done
-- I assume you'll only change x/y/width/height, as other properties are dynamic
-- Doing 'proxy.x = 123' is the same as 'object.border.x = 123' + recalculating
object.border[k] = v -- Actually apply the change
calculate() -- Recalculate the other properties that depends on the above
end;
})
gui.add(object)
return object.config.id
end
You can run code like proxy.x = 12 to edit the X property. All values will be recalculated. It's not the best, but your code a tiny bit annoying to improve. (But hey, if it works fine for you, it's good)
Note: You can only set x, y, width and height. You can get all properties the old way though, e.g. proxy.padding.width (Mind that proxy.x doesn't work. Use proxy.border.x)
Related
This question has some reference to the question Defining logical operator implies in lua.
The following code works fine.
local function _implies(a, b)
if a == 1 and b == 0 then return 0
else return 1 end
end
local my_right = {
__mul = function(self, b)
return _implies(self.a, b)
end
}
local _mt = {
__mul = function(a)
return setmetatable({a=a}, my_right)
end
}
local my_left={}
setmetatable(my_left,_mt)
imp = my_left
local names={}
for i = 0,1 do
for j=0,1 do
names.i=i;names.j=j
print(i, j, names.i *imp* names.j)
end
end
However the following code doesn't work.
str="i *imp* j"
local function _implies(a, b)
if a == 1 and b == 0 then return 0
else return 1 end
end
local my_right = {
__mul = function(self, b)
return _implies(self.a, b)
end
}
local _mt = {
__mul = function(a)
return setmetatable({a=a}, my_right)
end
}
local my_left={}
setmetatable(my_left,_mt)
imp = my_left
local names={}
for i = 0,1 do
for j=0,1 do
names.i=i; names.j=j
print(i, j, load("return " .. str,nil,"t",names)())
end
end
It gives the error that attempt to perform arithmetic on a nil value (global 'imp'). This is probably because imp is not available in names environment. Or is there any other reason? How imp can be made available inside environment names?
You hand names as the environment to the load function. The elements in names thus server as the global environment of the chunk you load. And that does not contain imp. To make it work, define names as follows: local names = { imp = imp }.
Then it will work.
Another option is to use local names = {}; setmetatable(names, {__index = _G}) to allow access to global variables (variables directly in the names table will "shadow" global variables though).
When replacing names, you will have to set the metatable again. Alternatively, don't replace the "names" environment, but rather just update the i and j fields instead: names.i = i; names.j = j
Let's say, for instance, I have two classes: A & B. I have set B as the handle class and would like a property from A to instantiate this class (i.e. B).
Therefore, I have done something like this in class A:
% Constructor
function a = A()
a.objB = B(); % This works fine
...
for i = 1:10
a.var(i) = B(); % This causes an error to occur
end
end
The error is listed below:
"Error using double Conversion to double from B is not possible.
The code snippet inside the for loop seems to work if I change a.var(i) = B(); to var(i) = B();.
Do you have any idea why this is?
Your .var field is probably initialized to a double when you make the assignment (maybe to []). Using a.var(i) = xxx cannot change the type of a.var.
Try resetting the value the first time it is used. EG
for i = 1:10
if i == 1
a.var = B(); % Overwrite the existing value
else
a.var(i) = B(); % Now append to that value
end
end
This will cause your a.var field to be reallocated every loop. Pre-allocated your array will make everything go much faster. The easiest way to pre-allocate is actually to just loop backwards, like this:
for i = 10:-1:1
if i == 10
a.var = B(); % Overwrite the existing value, allocated room for 10 elements
else
a.var(i) = B(); % Assign each element in turn, 9 through 1
end
end
I have a problem with a function in matlab. This specific function is for filtering light signals. As you can see below I added the coding I’ve used in the function and in the while loop itself. The code is written for a NXT Lego robot.
Is there any tip how to get the count variable ( i = i + 1 ) to work in the function, so we can plot Light(i)? Because we’re getting a bunch of error messages when we try different codes to make it work.
function [light] = filter_func( i)
lightI(i) = GetLight(SENSOR_3);
if i==1
light(i)=lightI(i)
elseif i==2
light(i) = 0.55*lightI(i) + 0.45*lightI(i-1)
else
light(i) = 0.4*lightI(i) + 0.3*lightI(i-1) + 0.3*lightI(i-2);
end
end
i=1
while true
lightI(i) = GetLight(SENSOR_3); % Get’s a lightvalue between 0 and 1024.
if i>2
light =filter_func(i)
light=round(light);
else
light(i) = GetLight(SENSOR_3);;
end
i=1+i
plot(light(end-90:end), 'r-');
title('Lightvalue')
axis([0 100 0 1023]) ;
end
You probably mainly get errors because you are not allowed to mix script and functions like this in MATLAB (like you are in Python).
Your filter function is only used when i>2 so why are you doing the first 2 tests? It seems like you want lightI as a global variable, but that is not what you have done. The lightI inside the function is not the same as the one in the while loop.
Since your while loop runs forever, maybe you don't need to worry about updating the plot the first two times. In that case you can do this:
filter = [0.4 0.3 0.3]';
latest_filtered_light = nan(90,1);
lightI = [];
p = plot(latest_filtered_light, 'r-');
title('Lightvalue')
axis([0 100 0 1023]) ;
while True
lightI(end+1,1) = rand*1024; % Get’s a lightvalue between 0 and 1024.
if i>=3
new_val = lightI(end-2:end,1)'*filter;
latest_filtered_light = [latest_filtered_light(2:end);...
new_val];
set(p, 'ydata', latest_filtered_light)
drawnow
end
end
I think it is an important point to not call plot every time - at least if you are the least concerned about performance.
In this example I'm trying to create an Array of length 5 where each ellement contains the number of times .3 can be summed without exceeding 1. i.e. 3 times. So each element should contain the number 3. Here is my code:
Array[(
workingCount = 0;
workingSum = 0;
done = false;
While[! done,
workingSum = workingSum + .3;
If[workingSum > 1, done = true; workingCount, workingCount++]
])
, 5]
In the 3rd to last line there I have workingCount without a ; after it because it seems like in Mathematica omitting the ; causes the value a statement resolves to to be returned.
Instead I get this:
{Null[1], Null[2], Null[3], Null[4], Null[5]}
Why does this happen? How can I get my program to do what I want it to do? i.e. In the context of the function passed to Array to initialize it's elements, how to I use complicated multi-line functions?
Thanks in advance.
Two things:
First, one way to be able to do that in Mathematica is
Array[
Catch[
workingCount = 0;
workingSum = 0;
done = False;
While[! done,
workingSum = workingSum + .3;
If[workingSum > 1,
done = True; Throw#workingCount,
workingCount++]]] &,
5]
Second, and most important: you never should do that in Mathematica! Really.
Please visit for example the Stack Exchange site for Mathematica, and read the questions an answers there to get some grip on the programming style.
Your problem comes from the fact that you are trying to initialize your array, but are trying to do so without an explicit function call - which is what you need to do.
See here for documentation on Arrays in Mathematica:
http://reference.wolfram.com/mathematica/ref/Array.html
That aside, and minor errors (True and False have to be capitalized), this is what you want to do:
f[x_] :=
(
workingCount = 0;
workingSum = 0;
done = False;
While[done != True, workingSum = workingSum + 0.3;
If[workingSum > 1, done = True, workingCount++]
];
Return[workingCount];
);
Array[f, 5] (* The array here is generating 5 values of the return value of f[x_] *)
Here's a example that I've to use when I want to create a button with mouse-over effect:
this.buttonExample.buttonMode = true;
this.buttonExample.useHandCursor = true;
this.buttonExample.addEventListener(MouseEvent.CLICK,myaction);
I'm new to AS3 - is there any way, to simplify this code like this:
this.buttonExample.buttonMode = true;.useHandCursor = true;.addEventListener(MouseEvent.CLICK,myaction);
why does it not works ?
Its already as simple as it gets. Firstly
this.buttonExample.buttonMode = true;
this.buttonExample.useHandCursor = true;
this.buttonExample.addEventListener(MouseEvent.CLICK,myaction)
is much more readable than
this.buttonExample.buttonMode = true;.useHandCursor = true;.addEventListener(MouseEvent.CLICK,myaction);
Always go for readbility over anything else. And secondly,
this.buttonExample.buttonMode = true;
does not return an object so you can't interact with anything.
If you're using that pattern a lot, you can make a helper function:
public function setAsButton(button:Sprite, clickHandler:Function):void {
button.buttonMode = button.userHandCursor = true;
button.addEventListener(MouseEvent.CLICK, clickHandler);
}
Then call it somewhere:
setAsButton(this.buttonExample, myaction);
If you feel that typing this.buttonExample over and over again is too repetitive, simply assign that object to a variable and use that variable in the rest of the statements:
var b : Button = this.buttonExample;
b.buttonMode = true;
b.useHandCursor = true;
b.addEventListener(...);
As other's have mentioned, there's also the with statement, but it's use is discouraged since it makes the code harder to read, and may lead to weird results:
with (this.buttonExample) {
buttonMode = true;
useHandCursor = true;
addEventListener(...);
}
You can, of course, combine these suggestions with other tricks, like chaining assignments:
var b : Button = this.buttonExample;
b.buttonMode = b.useHandCursor = true;
b.addEventListener(...);
Be very careful to only chain assignments in this way if the assigned value is immutable (e.g. true, false, numbers and strings, but not arrays or most other objects), because the same object will be assigned to all variables on the left side. If the value is immutable this doesn't matter, but if it's mutable you can end up with weird results, like this in this example:
a = b = [ ];
a.push(1);
b.push(2);
trace(a); // outputs 1, 2
trace(b); // also outputs 1, 2
The reason for this result is that a and b both reference the same array, and since arrays are mutable it doesn't matter how you access the object, it will still be changed. a and b don't reference different arrays just because they are different variables.
You may think that you could do something like the following, but it will not work.
// this will NOT work
var b : Button = this.buttonExample;
(b.buttonMode = b.useHandCursor = true).addEventListener(...);
The reason why it works to say b.buttonMode = b.useHandCursor = true, but not to add .addEventListener(...) is that the value of an assignment expression (e.g. b.buttonMode = true) is the value assigned to the left hand side (e.g. true). If you add .addEventListener(...) to that you are essentially saying true.addEventListener(...), which clearly is not what you want. In other words
b.buttonMode = b.useHandCursor = false;
is equivalent to
b.useHandCursor = false;
b.buttonMode = b.useHandCursor;
Which should hopefully also make the caveats mentioned above plain.
you can use the with statement. however I'd not encourage you to do so, since it leads to a lot of ambiguity and unclearness.
also, you can have multiple assignments:
this.buttonExample.buttonMode = this.buttonExample.useHandCursor = true;
this sometimes is useful, but for the sake of readability, you shouldn't overuse it.
greetz
back2dos